The objectives of the research proposal are to study the effects of hyperlipidemic serum and various serum lipoproteins on the synthesis of collagen by cultured smooth muscle and endothelial cells derived from human aortas. Since the intimal and medial layers of normal arteries contain predominantly Type III collagen and that intimal fibrous plaques consist primarily of Type I collagen, the synthesis of these two collagens will be investigated in cultured vascular cells grown in the presence of serum from Type II, III, and IV hyperlipoproteinemic patients, or in very low density (VLDL) and low density lipoproteins (LDL) from normo- and hyperlipidemic serum. Cultured cells will be incubated with tritiated proline and glycine ad the labelled collagens synthesized during this period will be isolated and purified by differential salt precipitation, gel electrophoresis, ion exchange and molecular sieve chromatography. To more clearly define any action of serum lipids on collagen metabolism the activity of several posttranslational modifying enzymes of the collagen polypeptide chains will be measured, including prolyl hydroxylase, procollagen peptidase and lysyl oxidase. These enzymes are involved in the hydroxylation, cleavage of the procollagen precursor and the cross-linking, respectively.